Phonograph



Sept. 22, 1942. E. A. ASH EIAL 2,296,489

PHONOGRAPH Filed Aug. 2, 1940 cg I v Patented Sept. 22, 1942 PHONOGRAPH Edward A. Ash, DetroiE Mich and Robert H. Larson, Geneva, Ill., assignors to Operadio Manufacturing Co., St. Charles, 111., a corporation of Illinois Application August 2, 1940, Serial No. 349,948

4 Claims.

This invention relates to phonographs, and particularly to the type employing a flat disc record which is usually mounted for rotation about its axis and carries on its face a spirally impressed groove or sound track with which a suitable stylus and sound reproducing and amplifying mechanism cooperate. In most constructions the stylus is carried by an arm pivoted at some distance from the axis of rotation to allow the stylus to swing toward or from the axis in following the sound track as the record rotates.

One object of the present invention is to provide a simple pivotal mounting for the stylus carrying arm or tone arm which shall be economical for manufacture and reliable in operation.

Another object is to provide an unusually compact arrangement of the tone arm and its pivotal mounting, permitting a machine of minimum dimensions to be operated with unusually large record discs.

More specifically it is an object of the invention to provide a mounting bracket for supporting the pivoted end of a phonograph tone arm or equivalent member upon a pivotal axis which is within the circumference of a record disc disposed in operative position on the turntable of the phonograph.

Other objects and advantages will appear from the following description taken in conjunction with the drawing in which:

Figure 1- is a top plan view of a small portable phonograph with this invention embodied therein.

Figure 2 is a fragmentary side elevation, partly in section, showing a mounting bracket as employed to pivotally support the tone arm in accordance with this invention.

Figure 3 is a detail section taken as indicated at line 3-3 on Figure 2.

Figure 4 is a detail section taken as indicated at line 44 on Figure 3.

In phonograph construction in which a turntable is provided for records of the flat disc type it has been customary to include a pivotally mounted arm carrying the stylus which engages the record groove in the upper face of the disc, and to mount such arm on a pivot at a substantial distance from the axis of rotation of the turntable so that in following the spiral record groove the stylus might swing over a path approximately radial to the axis of rotation and thus engage each successiveturn of the groove at almost the same angle. Obviously, this ideal would be more nearly approached by a relatively long stylus arm; but, on the other hand, practical considerations of size in building phonograph cabinets has held the length of the arm Within relatively close limits. And for portable machines in which the turntable is usually somewhat smaller than the ten or twelve-inch records commonly used upon it, and in which the casing upon which or within which the stylus arm is supported is of minimum dimensions, it is possible and satisfactory to employ a swinging arm intended to be pivoted at a point about seven inches from the center of the turntable, and having its stylus point somewhat less than eight inches from the pivot of the tone arm. But for certain purposes, and particularly for commercial records, operated in conjunction with picture projecting machines as for presenting illustrated sales talks and demonstrations, a sixteen-inch disc record has been found necessary to carry the required material. This invention permits the use of the same stylus arm with such a sixteen-inch record by providing a special mounting for the arm which supports it pivotally above the marginal portion of the record disc while the latter rotates on the turntable.

The invention is illustrated in conjunction with the preferred embodiment thereof in a small portable phonograph which employs the invention in a situation of maximum utility, but it should be understood that the invention itself is susceptible of manufacture in various forms and in combination with a variety of supporting structures. Accordingly, the present disclosure is to be considered as an exemplification of the principles of the invention, and it is not intended that the invention be limited thereto or thereby, but it is rather the intention to cover all modifications and alternative constructions falling within the spirit and scope of the invention as defined by the appended claims.

In the drawing, Figure 1 shows in plan view a relatively small portable phonograph including a case In, having a vertical spindle ll mounted for rotation by any suitable mechanism (not shown) within the case H). The spindle carries a turntable l2 on which there may be supported the flat type of record disc. The periphery of a ten-inch disc is indicated in dotted outline at l3, while that of a twelve-inch disc is indicated at M. The stylus carrying arm I5 is shown as of conventional design, having a terminal portion l6 in which it may be understood that there is housed an electrical pick-up device adapted to be actuated by the vibrations which the grooves of the record disc produce in a stylus, shown in Figure 1 in dotted outline at I! and secured near the end of the arm l5 by a set screw l8. The pick-up device at i6, which need not be shown or described for the purposes of the present invention, transforms the mechanical vi brations of the stylus into electrical impulses which are transmitted by means of a wire extending along the arm l5 and thence into the case I0, as seen at I9 '(Figure 2), where it is connected to operate suitable electrical amplifying apparatus (not shown) The arm I5 is carried on a, vertical pivot permitting the arm to swing in a horizontal plane so that its stylus I! may follow the spiral record groove of a disc record rotating on the'turntable 32. It is also necessary to provide for limited vertical play so that the stylus may track properly even if the record disc is slightly warped, or does not rest flatly upon the turntable, or for any other reason travels somewhat out of a plane strictly perpendicular to the axis' of rotation. For this purpose the said arm I5 at the end remote from the stylus I? has a pair of depending lugs 20 connected by a horizontal pivot 2| to upstanding lugs 22 of a small yoke which, in turn, carries the vertical pivot 23 on which the arm I5 swings through its horizontal range.

As indicated in Figurel, the pivot 23 is so located that its axis lies within the peripheral circle of a sixteen-inch record disc, denoted in dotted outline at 24. To meet the situation the pivot 23 is secured to a special bracket 25 which is formed to reach under and over the marginal portion of the large record disc. This bracket 25 is of generally U-shaped formation, and may be constructed from flat sheet metal stock bent to provide a horizontal leg 26 which is mounted on the top wall of the casing Ill, a mid-portion 2'! projecting vertically therefrom, and a second leg 28 which extends horizontally above the leg 26 in spaced relation thereto and in a plane above that of the large record disc, of which a fra ment is shown at 24 in Figure 2. The pivot 23 is fitted with suitable washers 29 and 30 disposed respectively above and below the arm 28 of the bracket 25 to insure easy pivotal action; and the yoke whose lugs 22 engage the pivot 2i includes 2. depending stop lug 3! which swings in an arcuate slot 32 formed in the upper leg 28 of the supporting bracket so as to definitely limit the horizontal travel of the arm I5 about the pivot 23 and thus prevent straining and injuring the electrical conducting wire IS. The wire, as seen in Figure 1. passes through aligned openings 33 and 34 in the upper and lower legs of the bracket 25.

The lower leg'ZB may be secured to the upper surface of the casing in in any convenient manner, as by bolts 35, and from Figure 1 it will be noted that the bracket is mounted at the extreme corner ofthe case I I), thus utilizing the greatest available distance from the spindle Ii within the area upon which the arm [5 can be given a footing. In this way, the apparatus is enabled to employ a shorter arm with over-size, sixteen-inchrecords which actually project beyond the pivot axis on which the arm swings, and it is found that the arc in which the arm moves when thus mounted is such that the stylus tracks perfectly in the record grooves of the large, sixteen-inch record disc.

The end of the stylus arm I5 which is adjacent the pivot 23 extends a short distance from the pivot axis but the pivot is so located on the overhanging portion not the bracket 25 that this end of the arm l5 terminates well within the area of the top wall of the casing I0, as clear- 1y seen in Figure 1. This relation permits enclosing the stylus arm IS with a suitable cover as indicated in dotted outline at 35 in Figure 2, which may be fitted closely onto the casing Ii! and conform to the outlines thereof so as to protect the parts for storage or transit. In constructions in which the turntable I2 extends beyond the outlines of the casing, as in the structure shown in Figure 1, the turntable itself may be made removable from the spindle for storage in another position in the casing.

We claim as our invention:

1. In a phonograph the combination of a rectangular casing, a spindle extending through the top wall of the casing nearer one end than the other with a turntable mounted on the spindle above said top wall to support a disc record, a stylus carrying arm to swing horizontally above the turntable, a bracket comprising a member formed of relatively thin sheet metal secured to the casing with a part of the bracket extending vertically upward from and substantially within the outline of the top surface of the casing and closely adjacent the corner farthest from the spindle and with a portion extending horizontally from the vertically disposed part and toward the spindle in a plane above that of the turntable, together with pivotal means on said horizontally extending portion connecting the stylus arm thereto, the portion of the arm adjacent said pivotal means terminating directly over the top wall of the casing and within the vertical planes of its edges.

2. In a phonograph the combination of a rectangular casing, a spindle extending through the top wall of the casing nearer one end than the other with a turntable mounted on the spindle above said top wall to support a disc record, a stylus carrying arm to swing horizontally above the turntable, a bracket comprising a U-shaped member formed of relatively thin sheet metal having a lower leg secured to the top surface of the casing with an adjoining part of the bracket extending vertically upward from said leg and closely adjacent the edge of the casing and with an upper leg extending horizontally from the vertically disposed part and toward the spindle in a plane above that of the turntable, together with pivotal means on said last mentioned leg connecting the stylus arm'thereto, said stylus arm including an electrical pick-up device and a flexible electrical conductor extending along the arm and adjacent said pivotal means, the upper and lower legs of the bracket having aligned apertures registered with an opening in the top wall of the easing and accommodating said conductor in the vicinity of said pivotal connection of the stylus arm to the bracket, said upper leg of the bracket having an arcuate slot concentric with the pivotal means, the stylus arm having a lug depending into said slot for limiting the swing of said arm upon its pivotal bearing.

3, In a. phonograph the combination of a rectangular casing, a spindle extending through the top wall of the casing'nearer one end than the other with a turntable mounted on the spindle above said top wall to support a disc record, a I

stylus carrying arm to swing horizontallyabove the'turntable, a bracket comprising a U-shaped member formed of relatively thin sheet metal having a lower leg secured to the top surface of the casing with an adjoining part of the bracket extending vertically upward from said leg and closely adjacent the edge of the casing and with an upper leg extending horizontally from the vertically disposed part and toward the spindle in a plane above that of the turntable, together with pivotal means on said last mentioned leg connecting the stylus arm thereto, said stylus arm including an electrical pick-up device and a flexible electrical conductor extending along the arm and adjacent said pivotal means, the upper and lower legs of the bracket having aligned apertures registered with an opening in the top wall of the casing and accommodating said conductor in the vicinity of said pivotal connection of the stylus arm to the bracket, said stylus arm including a yoke with upstanding portions pivoted to the arm at a horizontal axis, said yoke and the upper leg of the bracket having vertically registered apertures with a connecting pivot therein constituting the aforesaid pivotal connection between the arm and the bracket, said upper leg having also an arcuate slot concentric with the pivot axis and-the yoke having a lug E depending into the slot for limiting the swing of the stylus arm upon the pivot.

4. A bracket for supporting a stylus carrying arm on the top wall of a phonograph casing, said bracket comprising a U-shaped member having a horizontal leg to be secured against said top wall, a substantially vertical portion to extend upwardly from said leg, and a second leg to extend horizontally over the first in spaced relation thereto aflording clearance for the marginal portion of a record disc between the upper and lower legs, the upper leg having a pivot aperture for attachment of a stylus arm, and an arcuate slot to cooperate with a stop on such arm for limiting the swing thereof.

EDWARD A. ASH. ROBERT H. LARSON. 

